Calculations Used in Analytical ChemistryChapter 4

International System of Units / SI Units

Mass and Weight

The Mole

Concentrations of SolutionsFrom Liquids(More accurately, from stock solutions)

Common ConcentrationPercentppt, ppm, ppbMolarityMolalityNormality

Percent

ExampleIf 28.5g of calcium hydroxide is dissolved in enough water to make 185g of solution, calculate the % concentration of calcium hydroxide in the solutionIf 7.5g of sodium nitrate is dissolved in 85.0mL of water, calculate the percent concentration of sodium nitrate in the solution.

Example3. A wine contains 12% alcohol by volume. Calculate the number of milliliters.

parts per millionPpm = milligram of solute/kilogram of solutionsPpm = milligrams of solute/Liter of solutions

Parts per billionPpb = microgram/LiterPpb = (mass of solute/mass of solution) X 109

molality

molarity

NormalityWhere : Eq = mass of solute/ Eq weight

Eq weight = MW/F

Making molar solutions from liquidsNot all compounds are in a solid formAcids are purchased as liquids (stock solutions). Yet, we still need a way to make molar solutions of these compounds.The Procedure is similar:Use pipette to measure moles (via volume) Use volumetric flask to measure volumeNow we use the equation M1V1 = M2V21 is starting (concentrated conditions)2 is ending (dilute conditions)

1.How many mL of a 14 M stock solution must be used to make 250 mL of a 1.75 M solution?2.You have 200 mL of 6.0 M HF. What concentration results if this is diluted to a total volume of 1 L?3.100 mL of 6.0 M CuSO4 must be diluted to what final volume so that the resulting solution is 1.5 M?4.What concentration results from mixing 400 mL of 2.0 M HCl with 600 mL of 3.0 M HCl?5.What is the concentration of NaCl when 3 L of 0.5 M NaCl are mixed with 2 L of 0.2 M NaCl?6. What is the concentration of NaCl when 3 L of 0.5 M NaCl are mixed with 2 L of water?7.Water is added to 4 L of 6 M antifreeze until it is 1.5 M. What is the total volume of the new solution?8.There are 3 L of 0.2 M HF. 1.7 L of this is poured out, what is the concentration of the remaining HF?